Design And Analysis Of Multi-purpose High Efficiency Energy Conversion System Matched With Offshore Floating Small Lead Cooled Fast Reactor

The small lead cooled fast reactor on offshore floating platform requires the matching energy conversion system to have the characteristics of high energy conversion efficiency,safety and reliability,small size,light weight,etc.There are many existing energy conversion technology solutions,such as organic Rankine cycle,steam Rankine cycle,Brayton cycle,Stirling cycle and so on.Among them,Brayton cycle has the advantages of high energy conversion efficiency,high reliability and compact system arrangement,which can meet the needs of small lead-cooled fast reactor on offshore floating platform.However,in order to better match the design requirements of the energy conversion system and choose a suitable system solution for it,it is necessary to investigate the influence of the working medium,system layout and key parameters of the Brayton cycle on the cycle characteristics and carry out the system design work.In the research on the Brayton cycle at home and abroad,there is a lack of comprehensive and clear investigation of the characteristics of various working materials in the Brayton cycle under different temperature ranges.In the relevant research on cycle parameter design,the parameter range does not cover the temperature and pressure in this work,which leads to difficulties in the design of specific energy conversion system solutions at present.Therefore,it is necessary to conduct research on the characteristics of carbon dioxide,helium,air and nitrogen in the cycle and the influence of the key parameters of the cycle on the cycle efficiency under the system parameters(15-560℃,2.67-20 MPa)in this paper,to obtain the cycle performance of each working fluid and to select a suitable system solution.There are few studies on the coupling of energy conversion systems for other applications,so this article’s research on the coupling of seawater desalination systems and energy conversion systems will also be an important direction for the study of the multi-purpose characteristics of energy conversion systems.This paper uses THERMOFLOW software to conduct simulation research on modeling,design calculation,analysis of high efficiency energy conversion system.In terms of system layout and work fluids selection,the system adopts a closed Brayton cycle,and after quantitative calculations and comparative analysis of various work fluids(CO2,helium,air and nitrogen)applicable to the Brayton cycle,the calculations show that the efficiency of the system using CO2 is better than that of air and nitrogen under the temperature range of 15-560℃ and the three pressure conditions of 8MPa.13MPa and 20MPa,and the highest efficiency can reach 39.36%.Helium has the lowest efficiency in the high-efficiency energy conversion system,with the system efficiency below 30%under most conditions.In terms of system design,key parameters affecting system efficiency such as maximum system temperature,compressor pressure ratio,split ratio,maximum system pressure,and compressor inlet temperature are studied in the parameters set for the system to select the optimal parameter scheme.In terms of the multi-purpose characteristics of the system,the desalination system is coupled with the energy conversion system for calculation to improve the comprehensive efficiency of the system while obtaining fresh water.This paper finally proposes a multi-purpose high efficiency energy conversion system design scheme:S-CO2 Brayton recompression cycle,system thermal power of 50MW,maximum system temperature of 560℃,maximum system pressure of 20MPa,main compressor pressure ratio of 2.73,recompression pressure ratio of 2.714,shunt ratio of 0.69,main compressor inlet temperature of 30.2℃,system efficiency of 42.988%,fresh water output 254.016 t/d.